The Arch build system is a ports-like system for building and packaging software from source code. While pacman is the specialized Arch tool for binary package management (including packages built with the ABS), ABS is a collection of tools for compiling source into installable .pkg.tar.xz packages.

Ports is a system used by *BSD to automate the process of building software from source code. The system uses a port to download, unpack, patch, compile, and install the given software. A port is merely a small directory on the user's computer, named after the corresponding software to be installed, that contains a few files with the instructions for building and installing the software from source. This makes installing software as simple as typing make or make install clean within the port's directory.

ABS is a similar concept. ABS is made up of a directory tree that can be checked out using SVN. This tree represents, but does not contain, all official Arch software. Subdirectories do not contain the software package nor the source but rather a PKGBUILD file and sometimes other files. By issuing makepkg inside a directory containing a PKGBUILD, the software is first compiled and then packaged within the build directory. Then you can use pacman to install or upgrade your new package.

ABS overview

'ABS' may be used as an umbrella term since it includes and relies on several other components; therefore, though not technically accurate, 'ABS' can refer to the following tools as a complete toolkit:

SVN tree

The directory structure containing files needed to build all official packages but not the packages themselves nor the source files of the software. It is available in svn and git repositories.

shell command tool which reads the PKGBUILDs, automatically downloads and compiles the sources and creates a .pkg.tar* according to the PKGEXT array in makepkg.conf. You may also use makepkg to make your own custom packages from the AUR or third-party sources. See Creating packages for more information.

The Arch User Repository is separate from ABS but AUR (unsupported) PKGBUILDs are built using makepkg to compile and package up software. In contrast to the ABS tree on your local machine, the AUR exists as a website interface. It contains many thousands of user-contributed PKGBUILDs for software which is unavailable as an official Arch package. If you need to build a package outside the official Arch tree, chances are it is in the AUR.

Warning: Official PKGBUILDs assume that packages are built in a clean chroot. Building software on a dirty build system may fail or cause unexpected behaviour at runtime, because if the build system detects dependencies dynamically, the result depends on what packages are available on the build system.

SVN tree

The core, extra, and testingofficial repositories are in the packages SVN repository for checkout. The community and multilib repositories are in the community SVN repository.

Each package has its own subdirectory. Within it there are repos and trunk directories. repos is further broken down by repository name (e.g., core) and architecture. PKGBUILD's and files found in repos are used in official builds. Files found in trunk are used by developers in preparation before being copied to repos.

Easily compile and install a newer, older, beta, or development version of an Arch package by editing the version number in the PKGBUILD

ABS is not necessary to use Arch Linux, but it is useful for automating certain tasks of source compilation.

How to use ABS

To retrieve the PKGBUILD required to build a certain package from source, you can either use Svn or a Git-based approach using the asp package which is a thin wrapper around the svntogit repositories. In the following, the svn-based method as well as the git-based method is described.

Retrieve PKGBUILD source using Svn

Prerequisites

Non-recursive checkout

Warning: Do not download the whole repository; only follow the instructions below. The entire SVN repository is huge. Not only will it take an obscene amount of disk space, but it will also tax the archlinux.org server for you to download it. If you abuse this service, your address may be blocked. Never use the public SVN for any sort of scripting.

Build package

Then, copy the directory containing the PKGBUILD you wish to modify to a new location. There, make the desired modifications and use makepkg there as described in makepkg#Usage to create and install the new package.

Tips and tricks

Preserve modified packages

Updating the system with pacman will replace a modified package from ABS with the package of the same name from the official repositories. See the following instructions for how to avoid this.

Insert a group array into the PKGBUILD, and add the package to a group called modified.

PKGBUILD

groups=('modified')

Add this group to the section IgnoreGroup in /etc/pacman.conf.

/etc/pacman.conf

IgnoreGroup = modified

If new versions are available in the official repositories during a system update, pacman prints a note that it is skipping this update because it is in the IgnoreGroup section. At this point the modified package should be rebuilt from ABS to avoid partial upgrades.

Checkout an older version of a package

Within the svn repository you checked out as described in #Non-recursive checkout (i.e. "packages" or "community"), first examine the log:

$ svn log package-name

Find out the revision you want by examining the history, then specify the revision you wish to checkout. For example, to checkout revision r1729 you would do:

$ svn update -r1729 package-name

This will update an existing working copy of package-name to the chosen revision.

You can also specify a date. If no revision on that day exists, svn will grab the most recent package before that time. The following example checks out the revision from 2009-03-03:

$ svn update -r'{20090303}' package-name

It is possible to checkout packages at versions before they were moved to another repository as well; check the logs thoroughly for the date they were moved or the last revision number.